The present invention relates to a tank type gas circuit breaker, and more particularly to a tank type gas circuit breaker used for a three-phase alternating current.
In a conventional tank type gas circuit breaker, an arc-extinction gas is filled into three tanks that are juxtaposed and spaced in the air for insulation from each other and that incorporate therein interrupter parts for each phase, as shown in FIG. 1 of Japanese Utility Model Unexamined Publication No. 53-32361. In each of the interrupter tanks, there is provided an operational rotary shaft mechanism for driving a movable contact of the interrupter part incorporated within the interrupter tank. A connecting tank is fixedly provided for sealing the operational rotary shaft mechanism. The respective operational rotary shaft mechanisms are connected by operating rods that are connected to an actuator. Support legs are fixed to the respective interrupter tanks and are supported by a base fixed to the ground.
The interruption operation is performed as follows. A drive force produced by the actuator is transmitted to the operating rods, and the operating rods cause the respective operational rotary shaft mechanisms to rotate. Thus, the interrupter parts incorporated in the interrupter tanks are separated relative to each other to thereby complete the interruption operation.
The thus constructed tank type gas circuit breaker for a three-phase alternating current has bushing porcelain insulators that are mounted in parallel with each other. Accordingly, it is impossible to set a distance between the interrupter tanks to a distance less than the air-insulation distance. Thus, the conventional circuit breaker requires a large area for installation. Also, the respective interrupter tanks are independent of each other. Therefore, it is necessary to provide the connecting tank for each phase, which increases the number of the mechanical parts and the cost therefor. Furthermore, it is difficult to adjust the interruption timing between the respective phases. This needs a long period of time.
In contrast to the above-described conventional arrangement, there has been proposed another tank type gas circuit breaker for a three-phase alternating current as shown in FIGS. 2 and 3 of Japanese Utility Model Unexamined Publication No. 53-32361. In this tank type gas circuit breaker, the bushing porcelain insulators are arranged obliquely relative to each other to thereby keep the air insulation distance suitably, whereby the distance between the interrupter tanks for respective phases is reduced. Furthermore, the interrupter tanks are connected at their barrel portions by hollow connecting members. Operating rods are disposed within the hollow connecting members and the respective operational rotary shaft mechanisms are disposed within the respective interrupter tanks. Thus, it is possible to reduce the installation area and to dispense with the connecting tanks for sealingly incorporating the operational rotary shaft mechanisms.
However, since the above-mentioned tank type gas circuit breaker for the three-phase alternating current completes the assembling thereof after the interrupter parts are disposed within the interrupter tanks, performed must be the adjustment of the length of the connecting rods connecting the operational rotary shaft mechanisms and the contacts of the interrupter parts, namely, the adjustment of the interruption timing for the respective phases after the completion of the assembling of the circuit breaker and further within the interrupter tanks. Accordingly, it is necessary to provide a manhole for adjustment in a suitable position of each interrupter tank. Also, since the adjustment is carried out in the tanks, it is difficult to perform the adjustment. In addition, the provision of the operating rotary shaft mechanisms within the interrupter tanks makes the internal structure of each tank complicated. Although such an arrangement enables to dispense with the connecting tanks, it is difficult to reduce the number of the mechanical parts to simplify the structure and to enhance the reliability of the circuit breaker.